Nostalgia finally can be left behind, because it was all so real for the Islanders on Wednesday night. Their new digs at Brooklyn’s Barclays Center were no longer an abstract, but a home.

The Islanders played their Blue-and-White prospect scrimmage in front of 6,311 surprisingly engaged and paying fans, and 19-year-old Josh Ho-Sang, the 28th overall pick from the 2014 draft, stole the show with three assists.

There was hockey in the Borough of Kings, and now it’s here to stay.

“There has been a lot of anticipation over the last couple years, and now we’re just weeks away,” Islanders general manager Garth Snow said. “As you can you can see walking through the concourse, and all the Islander jerseys on the street, our fans have been tremendous.”

Snow carried a pool of reporters in his wake as he tromped through the corridors before the game, and then and out onto the street, occasionally stopping to shake hands and say hello. The anticipation was to see the new Islanders’ locker room and surrounding “campus,” but it was still far from completion. The extent of progress? Walls had been put up and the electricity seemed to be in place.

So the 10,000 square feet of plush accommodations the players and staff have so lauded — via artist renderings — are still some time away. The plan is for everything to be ready for preseason games — the first is Sept. 21 against the Flyers.

It will be quite a transition from the Nassau Coliseum, the crumbling and beloved building in Uniondale that was the only home the franchise had known since its inaugural season of 1972-73. Most of the Islanders’ players and staff still live on Long Island — as do the fans — where the team will practice.

“I think it’ll be an adjustment,” Snow said, “but hockey players, once they get into a routine, probably like any other professional athletes, I think it’ll be an easy transition.”

The Islanders Blue and White prospect scrimmage on Wednesday was held at the Barclays Center, the team’s new home.AP

The Islanders battled for first in the Metropolitan Division for the first half of last season, and then tapered off in the wake of injuries, eventually losing to the Capitals in a seven-game first-round series. Despite some big-time offseason moves from those within the division — most notably the Blue Jackets and Capitals — the Islanders are going in with just about the same team they had last year.

And Snow is fine with that.

“Barring injury, I think we’ll be better,” Snow said. “There are a lot of good teams in our division and our conference that maybe had a hiccup here or there because they ran into injury trouble. But we feel that we’ve built a team in the draft now that can compete with any team on any given night.”

The biggest move Snow has made this offseason is signing his own restricted free agents, Thomas Hickey and Anders Lee — the latter awkwardly coming along for the tour of the unfinished facilities. Center Brock Nelson remaining restricted and unsigned, but that negotiation likely won’t be completed until later in the summer. Veteran Thomas Greiss was signed to be the backup goalie.

Yet with quite a bit of time before training camp starts in September, the Islanders still have about $9.2 million in salary-cap room to sign or trade for a veteran. That’s what Snow did the week before training camp last season, taking advantage of the cap-strapped Blackhawks and Bruins and landing his top two defensemen, Johnny Boychuk and Nick Leddy, both of whom he then locked up to seven-year contracts.

“If a deal is going to help us be better, we’ll do it,” Snow said. “I think we’ve proven that the last couple years especially. Whether it’s a free-agent signing, whether it’s trading for players, bringing up young players that have cut their teeth in the AHL, we’ll look at any avenue of getting better.”

Now the foundation has been set, and so has the building. It’s officially a new age in Islanders history.